The invention relates to an apparatus and method for guiding and cutting a continuously advancing yarn during a package doff in a yarn winding apparatus.
The apparatus and method are known from EP 0 311 827. In textile machines, for example, a crimped yarn is continuously wound to a package. After the package is fully wound, same is doffed. To this end, it is necessary to first cut the yarn, so that the full package with the loose yarn end can be replaced with a new empty tube. During the doff, the yarn end of the continuously advancing yarn is received and removed by a pneumatic suction device. After the package is doffed, the yarn is caught by means of a catching device and wound on the new tube.
In the apparatus disclosed in EP 0 311 827 and by the known method, the yarn is guided, after the package is fully wound, by means of a movable yarn guide outside the winding range to a suction device laterally arranged next to the winding range. After the package is doffed and the new tube is ready for catching the yarn, the yarn guide swings back to the winding range. To transfer or respectively catch the yarn, same is deflected by means of a transfer device between the suction device and the yarn guide, and presented for catching to the catching device.
The known apparatus and the known method have the disadvantage that at the end of the winding cycle, the loose yarn end on the fully wound package lies there against in an undefined manner, which complicates locating the loose yarn end in particular during further processing.
Furthermore, the deflection of the yarn by the transfer device for purposes of catching the yarn leads to considerable loopings which result, when compared to the winding tension, in major tension fluctuations of the yarn. Such fluctuations in the tension may lead to a formation of laps on preceding feed elements.
It is accordingly an object of the present invention to provide an apparatus and a method of the initially described type which ensure that the yarn is guided as gently as possible while doffing the package, catching the yarn, and winding initial layers thereof.
A further object of the invention is to ensure that after cutting the yarn, the loose yarn end lies against a tie-off wind on the full package.